Geography, environmental conditions, disease and attack by insects are major factors influencing the ability to grow and cultivate different species of plant. Such factors can have a significant downstream economic and social impact on communities around the world. There would be benefit in identifying products and methods which might impart beneficial properties to a plant species to allow it to grow in a variety of geographical locations, in different weather conditions, to survive disease and to be resistant to attack by insects, for example.
There is an ever increasing demand for plants having other desirable characteristics such as improved quality, increased or decreased levels of certain compounds, improved or different taste, smell, colour or other physical or chemical properties.
Selective breeding techniques have been used to this end. Selective breeding relies principally on genetic diversity in a starting population coupled with selection to achieve a plant cultivar with characteristics beneficial for human use. As the available, unused genetic diversity of cultivatable plant species has diminished, the potential for improvement has decreased. This situation has stimulated the growth of plant genetic modification in which genes from closely related species are introgressed into the new cultivar to provide a new genetic base for imparting desirable traits into new cultivars. However, this process is extremely costly, slow, limited in its scope and fraught with regulatory difficulties. Few commercial successes have eventuated from over two decades of large-scale investment into this technology.
Despite many decades of successful scientific research into the conventional breeding of highly-productive crops and into development of transgenic crops, relatively little research effort has been directed at development of plant traits via other means.
The importance of providing “good” soil with a rich microbial diversity via composts, complex biomaterial fertilisers e.g. blood and bone, to plants to ensure their healthy growth has been understood by home gardeners' and producers of organic foods. However, the inventors have recognised that the complexity of the plant-microorganism associations that underpin the observable benefits is poorly understood. Benefits to plant growth and health in such soils are often microbially-mediated through improved nutrient availability. This may be the result of solubilisation of minerals from the soil biomass itself, or from colonization of the plants with microorganisms in endophytic, epiphytic or rhizospheric associations leading to nitrogen fixation, resistance to pests and diseases through direct microbial competition within the plant, or the elicitation of plant defence reactions. The science community has produced literature on the diverse mechanisms of endophytic, epiphytic and rhizospheric plant microorganism associations, largely in relation to crop plants and their soils. The nature of some associations is known, encompassing the genetic basis of plant-induced metabolite production by specific organisms and the reverse influence of the microbe on gene expression in the plant (e.g. Neotyphodium spp), and increases in plant growth following microbial application to certain crop plants or seeds has been documented. However, despite the potential of microorganisms to improve plant growth, commercial success is limited to a relatively small range of specific microbial applications e.g. Rhizobium spp. to legume seeds, or the use of products resulting from “uncontrolled” microbial fermentations e.g. compost teas, seaweed fermentations, fish waste fermentations etc.
There are many specific strains of potentially beneficial microorganisms for association with specific plant cultivars, making the task of finding an appropriate strain(s) for any particular crop a very onerous procedure. Current means primarily focus on the application of microorganisms singly or in limited combinations. Such microorganisms are likely to have been selected for specific potential properties based on their identity. It would be useful if there was no requirement for knowledge of microbial identity for success.
Bibliographic details of the publications referred to herein are collected at the end of the description.